1. Field of the Invention
This invention relates to methods and apparatus for manufacturing or repairing lug, trunnion, or other protruding members, attached to ingot molds. More particularly, this invention relates to a method for welding new or replacement lugs or trunnion members onto ingot molds used in the steel industry.
2. Description of the Prior Art
Various types of molds for preparation of steel ingots are conventionally used in steel mills. For example, various types of big end down molds, such as, the open top and bottle top molds are known, as are various types of big end up molds, e.g., open bottom, closed bottom and plugged bottom. Such molds generally have different types of members protruding from the sides thereof for purposes of either lifting, rotating or maneuvering the mold. Typically, for example, such protruding members take the forms of either lifting lugs or turning trunnions. Essentially, these protruding members may be defined as "handles" for the steel ingot molds and they are generally used for maneuvering the molds in the yards, on the mold trains, and in the process of stripping the cast ingot from the mold.
Ordinarily, these "handles" are cast into the mold at the iron foundary where the molds are initially manufactured and generally occur in pairs, on opposite side walls, either at the top and/or the bottom of the mold, depending on the nature of the particular steel making operation wherein the mold is to be used.
Such lugs and trunnions vary in size and shape according to the customs or needs of the particular steel making operation and the weight and bulk of these members are determined by the size and weight of the mold itself and weight of the steel poured into them. For example, an average lug might be 10 inches wide, 14 inches long and 8 inches high and rectangular in shape.
If such a lug is cast into the top center of one of the side walls of an ingot mold, its height may taper from 3 inches of the very top to a final height of 8 inches at the bottom. The form of the lug is generally determined by efforts to conserve metal and weight, to provide strength and to provide some type of lip on the member for purposes of handling by the overhead cranes generally utilized for such purposes in steel mills.
Steel ingot molds are subject to severe treatment in steel mills and complete breakage of lugs or large portions thereof is frequent. Generally, the lugs or protruding members are essentially torn from the mold either leaving no remaining protruding portion or a small broken portion or stump of the original lug or trunnion.
Very often, this renders a relatively expensive ingot mold completely useless inasmuch as it cannot be handled and maneuvered. If the mold has been damaged while it is empty, it is usually set aside to be destroyed at a later time. However, if a lug has been torn from the ingot mold while trying to strip the ingot, it is usually destroyed immediately in order to recover the ingot as soon as possible.
In either event, and particularly in the United States, such broken lugs, trunnions and other protruding members, constitute a great economic disadvantage.
Efforts at repairing such molds have generally been unsuccessful since the repaired lug must possess essentially the same strength as the new lug and conventional securing procedures do not produce a sufficiently strong attachment of the new lug to the ingot mold. Also, such processes have generally required relatively expensive equipment and have not resulted in sufficient savings to warrant their use in steel mills.